摘要
将一种商用活性炭在氮气保护下进行微波处理 ,采用元素分析、XRD、N2 物理吸附和CO化学吸附等表征手段 ,考察了微波处理对活性炭载体的化学组成、物相、表面织构和催化剂钌分散度的影响 .以微波处理的活性炭为载体 ,以钡或钡铯为助剂 ,制备了一系列钌催化剂 ,在SV =10 0 0 0h-1,p =10 0MPa和θ =4 30℃的条件下进行了氨合成活性评价 .结果表明 ,活性炭经微波处理后能有效地脱除非碳成分 ,提高炭载体的稳定性 ,制备的负载型钌催化剂不仅具有较高的钌分散度 ,而且在一定温度范围内能够防止金属粒子烧结 ,从而使催化剂的活性和稳定性明显提高 .例如 ,以未经处理的活性炭为载体制备的4 %Ru Ba Cs/C催化剂 ,其出口氨浓度为 9 2 3% ,经 1 0MPa ,5 2 0℃耐热 36h后 ,其出口氨溶解度下降至 7 39% ;而以经微波处理的活性炭 (CW5 )为载体制备的 4 %Ru Ba Cs/CW 5催化剂 ,出口氨浓度为 16 78% ,经相同条件耐热后 ,其催化活性基本不变 .
A commercial activated carbon was treated in nitrogen flow using a microwave device as heat source. The effect of microwave treatment of activated carbon on its composition, structure and texture, as well as ruthenium dispersion on it was investigated by elemental analysis, X ray diffraction, N 2 physisorption and CO chemisorption. It was found that the microwave treatment of activated carbon can eliminate carbon impurities, improve the stability of activated carbon support under the ammonia synthesis condition, at the same time, the surface area and porosity of activated carbon do not decrease obviously. With the microwave treated carbon as the support, the Ru catalysts has not only higher Ru dispersion, but also can protect the ruthenium particles from sintering, when the catalysts were reduced at higher temperature. The activity of a series of barium promoted or barium cesium promoted, carbon supported ruthenium catalysts for ammonia synthesis was measured at 10?000 h -1 , 10 0 MPa and 430 ℃. The result shows that the activity and stability of the carbon supported Ru catalysts are greatly improved with microwave treated carbon as the support. For example, with original carbon as the support, the ammonia concentration in the effluent for 4%Ru Ba Cs/C was 9 23%, after undergoing the conditions of 1 0 MPa and 520 ℃ for 36 h, the ammonia concentration would decrease to 7 39%. With CW5 as the support, the ammonia concentration in the effluent for 4%Ru Ba Cs/CW5 catalyst was 16 78%, after undergoing the above conditions, the catalyst activity would be unchanged.
出处
《催化学报》
SCIE
EI
CAS
CSCD
北大核心
2002年第6期562-566,共5页
基金
国家科技攻关计划项目 (2 0 0 1BA3 2 2C)
福建省重大科技项目 (2 0 0 0F0 0 2 )
福州大学科技发展基金项目 (XKJ(QD) 0 10 2 )
关键词
活性炭载体
催化性能
微波处理
钌
负载型催化剂
钡
铯
助剂
氨
合成
activated carbon, microwave treatment, ruthenium, supported catalyst, barium, cesium, promoter, ammonia synthesis
